Approved 15 months ago as a pneumococcal disease vaccine for adults—and promoted as the first shot designed for seniors—Capvaxive from Merck now has new data supporting its use in children and adolescents.
In the phase 3 Stride-13 study involving 882 participants aged 2 to 17 years who had completed primary pediatric pneumococcal vaccinations and had one or more chronic medical conditions increasing their risk of respiratory illness, Capvaxive demonstrated encouraging results on three key fronts.
In the primary immunogenicity endpoint, Capvaxive’s immune response at 30 days post-vaccination for 12 shared serotypes matched that of Pneumovax, the 23-valent polysaccharide vaccine available since 1983. For its nine unique serotypes, Capvaxive showed superior immune responses.
In a secondary endpoint, Capvaxive produced immune responses to all 21 strains it targets, as measured by serotype-specific opsonophagocytic activity (OPA) geometric mean titers (GMTs) 30 days after vaccination.
In the primary safety endpoint, rates of adverse events—including systemic, serious, and vaccine-related events—were generally similar between groups.
“Children and adolescents living with chronic medical conditions are at increased risk of pneumococcal disease and offering them additional protection is essential,” said Rotem Lapidot, M.D., chief of pediatric infectious diseases at Rambam Health Care Campus in Israel, and an investigator in the Stride-13 trial.
Lapidot added that children and adolescents could benefit from the broader protection Capvaxive provides against serotypes not covered by other pneumococcal vaccines for infants.
The results were presented at the 6th European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Conference on Vaccines in Lisbon, Portugal. Merck has stated it plans to share the data with global regulatory authorities.
“While Capvaxive was designed to specifically cover the serotypes that cause the majority of invasive pneumococcal disease cases in adults, findings from Stride-13 underscore its added potential to help protect children and adolescents who are at an increased risk,” said Paula Annunziato, who leads Merck’s infectious diseases and vaccines development.
Capvaxive’s value for adults aged 50 and older lies in its 21 serotypes, which account for 84% of pneumococcal disease cases in this age group—compared to 52% for the 20 serotypes in Prevnar 20 by Pfizer, which is licensed for both children and adults.
Sales of Capvaxive have grown steadily, from $50 million in Q4 2024 to $107 million in Q1 2025 and $129 million in Q2 2025.